如何折叠R中整数序列中的空隙？

Question

是否有一个方便的基R或包函数，用于折叠，或插值，在任何间隙之间的整数值的数字序列？我已经搜索过像dplyr::dense_rank这样的函数，但是在这种情况下，它们不起作用。下面的代码生成一个示例，在单个列(column =Grp)中开始编号序列：

> myDF <- data.frame(Grp = c(1,2.1,2.2,4.1,4.2,6.1,9))
> myDF   
  Grp
1 1.0    
2 2.1    
3 2.2    
4 4.1
5 4.2
6 6.1
7 9.0

下面是我想要更改输出的方式；下面我手动在每个Grp行的右侧添加一个列的值(“折叠”)，解释我试图导出的内容：

    > myDF   
      Grp    Collapse 
    1 1.0    Every sequence starts with 1 so leave Grp as is
    2 2.1    Integer gap between rows 1-2 is <= 1 so leave Grp as is
    3 2.2    Integer gap between rows 2-3 is <= 1 so leave Grp as is
    4 3.0    Integer gap between original rows 3-4 is not <= 1 so fill in the gap with the seq integer 
    5 4.1    Integer gap between rows 4-5 is <= 1 so leave Grp as is
    6 4.2    Integer gap between rows 5-6 is <= 1 so leave Grp as is
    7 5.0    Integer gap between original rows 5-6 is not <= 1 so fill in the gap with the seq integer 
    8 6.1    Integer gap between row 7-8 is <= 1 so leave Grp as is
    9 7.0    Integer gap between original rows 6-7 is not <= 1 so fill in the gap with the seq integer
   10 8.0    Integer gap between original rows 6-7 is not <= 1 so fill in the gap with the seq integer
   11 9.0    Integer gap between row 10-11 is <= 1 so leave Grp as is

Answer 1

你可以：

f <- floor(myDF$Grp)
s <- seq(min(f), max(f))
sort(c(myDF$Grp, s[!s %in% f]))
#[1] 1.0 2.1 2.2 3.0 4.1 4.2 5.0 6.1 7.0 8.0 9.0